无机有机复合材料Bi2Te3／PAn电化学嵌锂性能研究

采用机械共混法制备了复合材料Bi2Te3/PAn,并对其电化学嵌锂性能进行了研究.研究发现Bi2Te3/PAn快速充放电性能良好,在以100 mA·g-1的电流密度充放电时首次可逆容量为480 mAh·g-1,到第20个循环时容量保持在200mAh·g-1.通过非原位X射线衍射方法研究其嵌锂机理,发现Bi2Te3在首次放电时分解,在随后的循环中以Te和Bi为嵌锂中心进行可逆储锂.     

Ga、K双掺杂P型Bi_(0.5)Sb_(1.5)Te_3材料的制备及热电性能

采用真空熔炼和热压方法制备了Ga和K双掺杂Bi0.5Sb1.5Te3热电材料。XRD结果表明,Ga0.02Bi0.5Sb1.48-x Kx Te3块体材料的XRD图谱与Bi0.5Sb1.5Te3的XRD图谱对应一致,但双掺杂样品的衍射峰略微向左偏移。热压块体材料中存在明显的(00l)晶面择优取向。SEM形貌表明材料组织致密且有层状结构特征。Ga和K双掺杂可使Bi0.5Sb1.5Te3在室温附近的Seebeck系数有一定的提高,而双掺杂样品的电导率均得到了不同程度的提高,其中Ga0.02Bi0.5Sb1.42K0.06Te3样品的电导率得到较明显的改善。在300~500 K测量温度范围内,所有双掺杂样品的热导率高于Bi0.5Sb1.5Te3的热导率,在300 K附近双掺杂样品的ZT值得到提高,其中Ga0.02Bi0.5Sb1.42K0.06Te3样品在300 K时ZT值达到1.5。     

Electric and mechanical performances of Bi0.5Sb1.5Te3 prepared by spark plasma sintering

Thermoelectric (TE) materials are a kind of functional materials which can be used to convert directly heat energy to electricity or reversely.The thermoelectric effects hold great potential for application in power generation and refrigeration.Bi2Te3 and its alloys are well known as best TE materials currently available near room temperature.This paper studies respectively the effects of spark plasma sintering (SPS) on electric performance of Bi0.5Sb1.5Te3 thermoelectric materials that are prepared through vacuum melting and ball milling.Through X-ray Diffraction and cold field emission scanning electric microscope s4800, the phase constituent and microstructure of the TE materials samples were analyzed.Electric conductivity and power factor can be improved with the rise of Spark Plasma Sintering temperature (from 300 to 500 ℃) and pressure(from 30 to 60 MPa), and the density and mechanical strength of Bi0.5Sb1.5Te3 thermoelectric material increase, too.     

Effects of hot pressing on electric performances of Bi0.5Sb1.5Te3

The effects of hot pressing on electric performance and mechanical strength of Bi0.5Sb1.5Te3 thermoelectric material prepared through vacuum melting and milling were studied. The phase constituent and microstructure were analyzed by X-ray Diffraction and cold field emission Scanning Electric Microscope. Aeolotropisms of the material on microstructure and electric performances are approved. With the rise of hot pressing temperature (from 300-500 ℃) and pressure (30-70 Mpa), electric conductivity and power factor are improved. Moreover, Bi0.5Sb1.5Te3 material can gain ideal thermoelectric performances and increased mechanical strength by hot pressing.     

急冷甩带过程和过量Te对p型Bi0.5Sb1.5Te3化合物热电性能的影响

采用感应熔炼制备得到了P型Bi0.5 Sb1.5Te3+x％(质量)Te(x=0、2、4和6)合金.将合金均匀分成R和S两组,R组不作处理,S组通过急冷甩带过程获得厚度约为5～15 μm的薄带,然后将两组样品分别粉碎过筛后,热压烧结成块体材料.利用扫描电镜(SEM)观察了薄带和烧结块体的形貌结构,在室温下测量其电性能....     

定向生长Bi2Te3-Sb2Te3三元合金热电材料的组织与性能

利用Bridgman定向凝固法,在大凝固速率范围内5～1000μm/s制备出Bi2Te3-Sb2Te3三元合金块体热电材料,并对其凝固组织和不同凝固速率下合金的热电性能进行研究。结果表明:高温度梯度和大凝固速率范围内制备的25%Bi2Te3-75%Sb2Te3合金定向凝固组织由Bi0.5Sb1.5Te3单相组织组成;在较低凝固速率5μm/s下,熔体生长平界面失稳形成胞状组织,而随定向凝固速率的增加,胞状组织减少,组织细化。不同定向凝固速率下25%Bi2Te3-75%Sb2Te3合金的Seebeck系数和电阻率随着凝固速率的增加而增大。50μm/s下300～450K范围内获得功率因子(PF)在4.6×10-3～5.01×10-3W/(K2.m),并在350K时PF值达到最大值5.01×10-3W/(K2.m);而在高凝固速率500μm/s下,其功率因子也可达4.5×10-3W/(K2.m),表明高温度梯度和大凝固速率制备热电材料是一种有效的制备工艺方法。     

~(60)Co Gamma Irradiation and Annealing Effects on Transport Properties of Antimony Telluride Platelets Grown by Physical Vapor Deposition

Physical vapor deposition method was employed to deposit antimony telluride(Sb2Te3) crystals in a dual-zone furnace. The microstructure, surface topography and composition of samples were characterized using X-ray diffraction,atomic force and scanning electron microscopy. Seebeck coefficient(S\c), electrical conductivity(r\c) as well as power factor(PF) were enhanced for pure Sb2Te3 samples upon annealing, and the samples annealed at 473 K exhibited the highest PF of 3.16 9 10-3W m-1K-2with an enhancement of 22% in the figure of merit(Z). When the delivered dose of60 Co gamma radiation was increased from 0 to 30 k Gy in the stoichiometric crystals, r\c decreased due to the decrease in mobility. As a result of the increase in S, PF and Z improved by 12.11 and 13.7%, respectively, in the 30 k Gy gammairradiated crystals. Both RH(B||c) and S\c were positive, suggesting that the prepared Sb2Te3 crystals retained the p-type semiconductivity after these treatments.     

DC conductivity study of polyaniline and poly(acrylonitrile-butadiene-styrene) blends

In this study, conducting blends of poly(acrylonitrile-butadiene-styrene) and polyaniline doped with dodecylbenzene sulfonic acid were prepared by solution blending. In order to understand the electrical conduction mechanism of the samples, DC electrical conductivity measurements of the blends were carried out in the temperature range of 80–320 K. The experimental results fit well with Mott's model of three-dimensional variable range hopping conduction. The values of Mott's temperature, density of states at the Fermi energy, average hopping distance and barrier height for the composites were calculated and presented.     

Gamma Irradiation Effects in InBi_(0.8) Te_(0.2) Crystals Grown by Horizontal Directional Freezing

The high-energy gamma-ray irradiation treatment using Co-60 isotope offers the possibility of engineering mechanical and optoelectronic properties of In Bi0.8Te0.2crystals. Tellurium-doped indium bismuthide(In Bi) crystals were prepared by horizontal directional freezing technique. Dose-dependent modifications in structure, composition and surface topographical features have been analyzed by X-ray powder diffraction, X-ray energy-dispersive analysis, transmission electron and atomic force microscopy, respectively. Dielectric constant and dielectric loss were found to increase with the cumulative dose of radiation, and a shift in the ferroelectric transition temperature(Tc) from 405 to 410 K was observed for25 k Gy. Upon irradiation, there is an enhancement in microhardness(HV), yield stress(ry) and stiffness constant(C11).The optical transmittance was decreased by 12.45%, resulting in a reduction in the optical band gap from 0.210 e V to0.198 e V. These results indicate the suitability of In Bi0.8Sb0.2crystals for low-wavelength infrared applications.     

SPS法制备的三元合金Ag0.405Sb0.532Te的热电性能

采用放电等离子烧结法(SPS)制备了三元合金Ag0.405Sb0.532Te,并研究了它的输运性能,即Seebeck系数、电导率和热导率。结果表明,当温度从316K上升到548K时,电导率从7.6×104S·m-1下降到6.6×104S·m-1。在438K以上,热导率随温度上升逐渐增加,低于438K时,热导率趋于稳定,约为0.86W·(K·m)-1。无量纲热电优值ZT在548K时取得最大值0.65,稍高于Ag0.365Sb0.558Te三元合金的0.61。与掺Ag的AgxBi0.5Sb1.5-xTe3(x=0～0.4)合金相比,热电性能得到了改善。并再次讨论了AgxBi0.5Sb1.5-xTe3合金中析出的第二相Ag-Sb-Te三元合金的作用机制。     

Effect of Two Synthetic Methods of Polyimide/Poly(Vinylidene Fluoride) Composites on Their Dielectric Properties

All-organic polyimide (PI)/poly(vinylidene fluoride) (PVDF) dielectric composites were fabricated via two synthesis methods. The dielectric and thermal properties of the PI/PVDF composites were investigated. The results indicated that the dielectric properties of the composites synthesized by these two methods were enhanced through the introduction of PVDF, and the composites exhibited excellent thermal stability. In addition, the composites prepared by solution blending exhibited superior dielectric properties and thermal properties compared with the composites prepared by in situ polymerization.     

High dielectric constant polyaniline/poly(acrylic acid) composites prepared by in situ polymerization

An ultra-high dielectric constant composite of polyaniline, PANI–DBSA/PAA, was synthesized using in situ polymerization of aniline in an aqueous dispersion of poly-acrylic acid (PAA) in the presence of dodecylbenzene sulfonate (DBSA). The water-soluble PAA served as a polymeric stabilizer, protecting the PANI particles from macroscopic aggregation. A very high dielectric constant of ca. 2.0 × 10⁵ (at 1 kHz) was obtained for the composite containing 30% PANI by weight. The influence of the PANI content on the morphological, dielectric and electrical properties of the composites was investigated. The frequency dependence of dielectric permittivity, dielectric loss, loss tangent and electric modulus were analyzed in the frequency range from 0.5 kHz to 10 MHz. SEM micrograph revealed that composites with high PANI content (i.e., 20 wt%) consisted of numerous nano-scale PANI particles that were evenly distributed within the PAA matrix. The high dielectric constants of these composites were attributed to the sum of the small capacitors of the PANI particles.     

添加Sb的Ga2Te3合金热电性能

本研究采用等摩尔分数的Sb元素替换Ga2Te3中的Ga元素,并利用放电等离子烧结技术制备Ga1.9Sb0.1Te3合金,研究其微观结构和热电性能。结果表明,添加Sb元素后,材料的Seebeck系数为130～240μV/K,明显低于单晶Ga2Te3,电导率为3600～1740??1·m?1,至少是单晶Ga2Te3的17倍,热导率提高近25%。在649K时Ga1.9Sb0.1Te3合金的热电优值(ZT)达到最大值0.1,是同温度下单晶Ga2Te3ZT值的3倍。     

机械合金化法制备的Mn15Bi34Te51和La15Bi34Te51热电材料

用机械合金化法制备了Mn15Bi34Te51和La15Bi34Te51合金，XRD分析表明Mn15Bi34Te51和La15Bi34Te51分别在真空球磨150h和100h后实现合金化，La15Bi34Te51在真空球磨150h后形成了纳米结构的合金，镧原子的加入有助于Bi2Te3基合金的晶粒细化及非晶化。对La15Bi34Te51合金的XRD结构分析表明镧原子有可能进入了Bi2Te3层状结构的Te-Te原子层间。La15Bi34Te51合金Seebeck系数的测量表明当晶粒尺寸减小到纳米尺寸时，载流子散射机制有可能发生改变，导致了Seebeck系数的大幅上升。     

Microstructure and mechanical properties of Mg-Cu-Y-Zn bulk metallic glass matrix composites prepared in low vacuum

Mg-Cu-Y-Zn bulk metallic glasses(BMG) and in situ bulk metallic glass matrix composites were prepared by copper mold casting under the low vacuum with the argon atmosphere,and the raw materials used in preparing the Mg-Cu-Y-Zn alloys were commercially pure materials.The microstructures of the bulk samples were analyzed by X-ray diffractometer(XRD) and the thermal stability of samples was investigated by using a differential scanning calorimeter(DSC).The thermal stability of sample prepared with commercia...     

部分填充Skutterudite化合物La_yCo_(4-x)Fe_xSb_(12)与未填充Skutterudite化合物Co_(4-x)Fe_xSb_(12)的制备及热电性能(英文)

采用机械合金化-热压成形-退火工艺制备了部分填充Skutterudite化合物LayCo4-xFexSb12（x≤1,y≤1）,对比研究了填充化合物LayCo3.5Fe0.5Sb12与未填充化合物Co3.5Fe0.5Sb12的热电性能。结果表明,稀土元素La的填充使热导率显著下降,但同时也降低了功率因子,导致材料热电优值上升不大。因此,要提高材料热电优值,还须优化材料电性能。     

Thermoelectric properties of Bi_（1.5）Pb_（0.5）Sr_（2-x）La_xCo_2O_y polycrystalline materials

Polycrystalline samples of Bi 1.5 Pb 0.5 Sr 2-x La x Co 2 O y (x = 0.1, 0.2, 0.3) with a layered structure were prepared by solid-state reaction method. All samples are p-type semiconductors. The thermoelectric properties, namely, the electric resistivity (ρ), Seebeck coefficient (S), and power factor (S 2 /ρ) of the samples are dependent on chemical composition. The values of ρ, S, and S 2 /ρ increase with an increase in temperature for all samples. The substitution of Pb 2+ for Bi 3+ and La 3+ for Sr 2+ improves the thermoelectric properties of the Bi 2 Sr 2 Co 2 O y system owing to the simultaneous decrease of electric resistivity and increase of Seebeck coefficient. As a result, the optimal thermoelectric property has been obtained in Bi 1.5 Pb 0.5 Sr 1.7 La 0.3 Co 2 O y and the power factor can reach 2.1 × 10-4 W·m-1 K-2 at 998 K.     

热压对(Mg2Ni+Mg3Sb2)/Mg复合材料组织及性能的影响

采用粉末冶金工艺制备了不同Ni含量的(Mg2Ni+Mg3Sb2)/Mg基复合材料,并采用热压工艺对已制备的复合材料进行塑性变形处理,研究了热压对(Mg2Ni+Mg3Sb2)/Mg基复合材料显微组织及力学性能的影响。结果表明,热压变形可以细化基体Mg颗粒,提高Mg3Sb2和Mg2Ni相分布均匀性,消除材料中的孔洞和裂隙等缺陷,提高复合材料的致密度,同时,使复合材料的力学性能得到显著提高。     

Ga、K双掺杂对N型Bi_2Te_(2.7)Se_(0.3)材料热电性能的影响

采用真空熔炼及热压方法制备了Ga和K双掺杂N型Bi2Te2.7Se0.3热电材料。XRD分析结果表明,Ga和K已经完全固溶到Bi2Te2.7Se0.3晶体结构中,形成了单相固溶体合金。SEM分析表明,材料组织致密且有层状结构特征。通过Ga和K部分替代Bi,在300~500 K的大部分温度范围内,Ga和K双掺杂对提高Bi2Te2.7Se0.3的Seebeck系数产生了积极的作用,同时双掺杂样品的电导率也得到明显的提高。Ga和K双掺杂样品的热导率都大于未掺杂的Bi2Te2.7Se0.3,Ga0.02Bi1.94K0.04Te2.7Se0.3合金在500 K获得ZT最大值为1.05。